Abstract:To evaluate the effects of blue light and sucrose on anthocyanin accumulation and chalcone synthase gene (CHS) expression, the leaves of 13-day-old seedlings of wild type Arabidopsis (WT) and hy4 mutant grown under 20μmol m-2 s-1 white light were used in the experiments. After irradiation by blue light (BL), anthocyanin content in leaves of WT increased with the increase of blue light intensity and irradiation duration. Anthocyanin content in hy4 mutant was lower than that in WT after BL treatment, which demonstratedthat cryptochrome 1(cry1)mediated the BL response in anthocyanin accumulation．CHS gene expression detected by Northern blot in the、WT leaves was induced by BL and it could be detected after 4 hours and reached a peak after 8 hours，and then the gene expression declined．BL could not induce any gene expression in hy4 mutant indicating cryl is the photoreceptor mediating the blue-light-induced CHS gene expression． It was observed that the increase ofan thocyanin an d gene expression were weakened in sucrose-free medium under blue light treatment． Sucrose may act not only as an energy source but also a component in blue-light-induced signal transduction of anthocyanin accumulation and CHS expression.